Let me get this straight. Many acknowledge that properly explaining EMdrive thrust may require new physics. Here, Todd has boldly proposed some pretty new physics. And a paper published by Nature just yesterday supports this new framework?I have to say - this is pretty damn amazing. Keep up the great work guys, and please let's all keep an open mind! It takes courage to publicly state and defend one's own views and if there's one thing EVERYONE can agree on, its that the truth is out there. If we support each other, we just might find it!
Quote from: ElizabethGreene on 06/16/2015 07:23 pmI have the following design equation for a box resonator.L,M,N being the number of half wavelengths for the box dimensions d,b,a respectively.Is there a similar equation for truncated cone shaped resonators? I do not trust my ability to derive it.Thanks.Here is a closed-form solution for a cylindrical cavity: https://en.wikipedia.org/wiki/Microwave_cavity#Cylindrical_cavityYou need a table of values for the zeros Xmn of Bessel Cylindrical function and the zeros X'mn of its derivative, here you have such a table, to 15 digits:http://wwwal.kuicr.kyoto-u.ac.jp/www/accelerator/a4/besselroot.htmlxYou also have to separately calculate the cut-off frequency (https://en.wikipedia.org/?title=Cutoff_frequency#Waveguides) for different modes to verify that they are not cut-off, when using the closed-form solution and the table of values.There is no closed-form solution for a truncated cone cavity.There are exact solutions for the truncated cone, but you have to solve two separate eigenvalue problems, one eigenvalue problem in terms of Legendre Associated functions and another eigenvalue problem in terms of spherical Bessel functions.Greg Egan shows an exact solution for modes that are constant in the azimuthal direction: TE0np and TM0np, here: http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.htmlTheTraveller has constructed an Excel spreadsheet solution based on Shawyer's ad-hoc approximation which approximates the truncated cone as large number of small cylindrical waveguides. The problem is that he still uses equations that are based on a cylinder. The electromagnetic field inside a cylinder has a longitudinal variation described by harmonic functions (sines and cosines, depending on the longitudinal mode number "p"). Instead, the electromagnetic field inside a truncated cone varies according to spherical Bessel functions.For an approximate solution you might as well use the cylindrical cavity exact solution: https://en.wikipedia.org/wiki/Microwave_cavity#Cylindrical_cavityand use the Mean of the Big and Small diameters as the diameter of the cylinder.
I have the following design equation for a box resonator.L,M,N being the number of half wavelengths for the box dimensions d,b,a respectively.Is there a similar equation for truncated cone shaped resonators? I do not trust my ability to derive it.Thanks.
..Await your data.
Is it really correct to view an EM drive as a closed system? For instance, as far as I know, no one has measured the external magnetic fields these things throw off. Most experiments use copper fustrums and so they must be coupled electromagnetically to the outside world.
Quote from: TheTraveller on 06/16/2015 11:55 pm..Await your data.I am writing a paper showing why it is wrong to use for truncated cones the cut-off frequency equations based on cylinders, as you are doing in your spreadsheet. The paper will show how can EM Drive researchers exploit the fact that cut-off frequencies for truncated cones do not work the way you are modeling it.The results are very interesting as they support some of the stuff that Todd has been writing about :-) .
Quote from: rfmwguy on 06/16/2015 02:37 pmYou might want to bookmark this link: http://www.ustream.tv/channel/em-drive-experimentThis is my eustream video channel where I will try and broadcast a live 1st test of my humble DIYDrive experiment in July. I may upload some videos in the meantime as I get further into the build.I have set chat up as well, but only plan to use it after a video upload or live event. I won't be routinely monitoring it. I'll hang here for most interactions.For now, you can log on to ustream for free, preferably creating the same username as you have on NSF, so I will know who I'm chatting with.Oh, forgot to mention. Click FOLLOW once your account is created, then you'll receive notices when uploads occur.If you share your dimensions,, flat or spherical end plates, Rf source (bandwidth if known) & excitation mode, I'll create a ss for your project.
You might want to bookmark this link: http://www.ustream.tv/channel/em-drive-experimentThis is my eustream video channel where I will try and broadcast a live 1st test of my humble DIYDrive experiment in July. I may upload some videos in the meantime as I get further into the build.I have set chat up as well, but only plan to use it after a video upload or live event. I won't be routinely monitoring it. I'll hang here for most interactions.For now, you can log on to ustream for free, preferably creating the same username as you have on NSF, so I will know who I'm chatting with.Oh, forgot to mention. Click FOLLOW once your account is created, then you'll receive notices when uploads occur.
Quote from: Rodal on 06/17/2015 12:00 amQuote from: TheTraveller on 06/16/2015 11:55 pm..Await your data.I am writing a paper showing why it is wrong to use for truncated cones the cut-off frequency equations based on cylinders, as you are doing in your spreadsheet. The paper will show how can EM Drive researchers exploit the fact that cut-off frequencies for truncated cones do not work the way you are modeling it.The results are very interesting as they support some of the stuff that Todd has been writing about :-) .You seem to be trying to void my question.The SPR software predicts the frequency used in the Flight Thruster tests. My ss version of the SPR software reports the same frequence. The Flight Thruster is a real device that has reported thrust while operating at 3.85GHz.Please share the resonant frequency your method reports using my dimensions. I suggest that if it does not report 3.85GHz, then it is wrong.As for Todd's theory, it may well be correct but like the use of dielectrics only produce weak thrust. Roger Shawyer has made a very clear comment about dielectrics and cutoff. 1) Dielectrics should not be used as they reduce Q and increase losses.2) Run the small end plate just ABOVE cutoff. To get Todd's condition, the small end needs to run BELOW cutoff, which is opposite to the advise of Roger Shawyer.
Quote from: TheTraveller on 06/16/2015 11:07 pmQuote from: rfmwguy on 06/16/2015 02:37 pmYou might want to bookmark this link: http://www.ustream.tv/channel/em-drive-experimentThis is my eustream video channel where I will try and broadcast a live 1st test of my humble DIYDrive experiment in July. I may upload some videos in the meantime as I get further into the build.I have set chat up as well, but only plan to use it after a video upload or live event. I won't be routinely monitoring it. I'll hang here for most interactions.For now, you can log on to ustream for free, preferably creating the same username as you have on NSF, so I will know who I'm chatting with.Oh, forgot to mention. Click FOLLOW once your account is created, then you'll receive notices when uploads occur.If you share your dimensions,, flat or spherical end plates, Rf source (bandwidth if known) & excitation mode, I'll create a ss for your project.Sure, flat endplates, 11.01 x 6.25 x 9 inch (dia big x dia small x ht), 8W CW source (no am/fm/phase modulation @ 2.450 Ghz. More info here: http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=978733
If Roger Shawyer cannot provide experimental proof of what mode shape he was operating at, the proper verification of a code should be based on mode shape TM212 with the NASA truncated cone, since that is the only one for which we have experimental verification.______________________________________________Actually, since you are working on this, to my knowledge, Shawyer did not provide (in his publications) the experimentally measured Q for the Flight Thruster, either. Do you know of a publication from Shawyer giving the Q, so that we can put this information in the wiki Experimental Data table ?
This is probably easily debunked, but it does pertain to Conservation of Momentum. Couple days ago, I was at a lake. Glass calm, no waves, no current.I loaded myself into a canoe for a little spin. Got out into the water. Drifted to a complete or near complete halt. Then...while remaining seated AND hands holding on tight to the side of the canoe, I 'threw' my torso forward. I never actually left the seat. But the canoe did move in that direction. I then straightened myself up (slowly) and repeated the process a few times. Each time, the canoe would shoot forward (ok move forward at less than paddle speed) for about two yards or so...but there was never any corresponding 'back motion' when I straightened.So...violation of CoM or something else? And could what I was doing be used as an analogy for whatever is going on with the EM Drive?
Quote from: demofsky on 06/16/2015 07:15 pmIs it really correct to view an EM drive as a closed system? For instance, as far as I know, no one has measured the external magnetic fields these things throw off. Most experiments use copper fustrums and so they must be coupled electromagnetically to the outside world. True, there is no real magnetic insulator and the best you can do is reroute the fields with a metal like iron or steel, but copper no. Copper will allow you in a moving electric field to induce another field within it (like the old trick of a magnet dropped through a copper pipe. http://video.mit.edu/watch/physics-demo-lenzs-law-with-copper-pipe-10268/) and corresponding eddy currents that in effect create their own magnetic field.Shell
Quote from: Rodal on 06/17/2015 12:36 amIf Roger Shawyer cannot provide experimental proof of what mode shape he was operating at, the proper verification of a code should be based on mode shape TM212 with the NASA truncated cone, since that is the only one for which we have experimental verification.______________________________________________Actually, since you are working on this, to my knowledge, Shawyer did not provide (in his publications) the experimentally measured Q for the Flight Thruster, either. Do you know of a publication from Shawyer giving the Q, so that we can put this information in the wiki Experimental Data table ?Shawyer has stated, several times, the Flight Thruster Q as 50 to 60,000 and he told me the mode was TE013.As for proof, I gave him my dimensions and desired mode (TE013), he gave me the frequency, which matched what I got using the SPR method in my SS, which matches what he used to excite the Flight Thruster. As far as I'm concerned, Game Over. His method correctly predicts the resonant TE013 frequency as 3.85GHz.When can I expect YOUR resonance date for the dimensions and frequency I provided?
Quote from: TheTraveller on 06/17/2015 01:07 amQuote from: Rodal on 06/17/2015 12:36 amIf Roger Shawyer cannot provide experimental proof of what mode shape he was operating at, the proper verification of a code should be based on mode shape TM212 with the NASA truncated cone, since that is the only one for which we have experimental verification.______________________________________________Actually, since you are working on this, to my knowledge, Shawyer did not provide (in his publications) the experimentally measured Q for the Flight Thruster, either. Do you know of a publication from Shawyer giving the Q, so that we can put this information in the wiki Experimental Data table ?Shawyer has stated, several times, the Flight Thruster Q as 50 to 60,000 and he told me the mode was TE013.As for proof, I gave him my dimensions and desired mode (TE013), he gave me the frequency, which matched what I got using the SPR method in my SS, which matches what he used to excite the Flight Thruster. As far as I'm concerned, Game Over. His method correctly predicts the resonant TE013 frequency as 3.85GHz.When can I expect YOUR resonance date for the dimensions and frequency I provided?In other words, Shawyer never experimentally verified that the mode shape of resonance was TE013, all he knew was that the EM Drive was resonating and he apparently just assumed that it must have been TE013 because his calculations told him to be so? No experimental mode shape verification? If so, the only valid data point for code verification remains TM212 from NASA Eagleworks. We cannot verify codes based on second-hand information from Shawyer (he has not published those values) and where there has not even been experimental verification of the mode shape.Concerning the Q value for the Flight Thruser all the other Q's in the wiki have been reported directly by the researchers. For consistency, we need a publication from Shawyer where directly reports the Q for the flight. thruster
Quote from: rfmwguy on 06/17/2015 12:28 amQuote from: TheTraveller on 06/16/2015 11:07 pmQuote from: rfmwguy on 06/16/2015 02:37 pmYou might want to bookmark this link: http://www.ustream.tv/channel/em-drive-experimentThis is my eustream video channel where I will try and broadcast a live 1st test of my humble DIYDrive experiment in July. I may upload some videos in the meantime as I get further into the build.I have set chat up as well, but only plan to use it after a video upload or live event. I won't be routinely monitoring it. I'll hang here for most interactions.For now, you can log on to ustream for free, preferably creating the same username as you have on NSF, so I will know who I'm chatting with.Oh, forgot to mention. Click FOLLOW once your account is created, then you'll receive notices when uploads occur.If you share your dimensions,, flat or spherical end plates, Rf source (bandwidth if known) & excitation mode, I'll create a ss for your project.Sure, flat endplates, 11.01 x 6.25 x 9 inch (dia big x dia small x ht), 8W CW source (no am/fm/phase modulation @ 2.450 Ghz. More info here: http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=978733Your SS attached.A quick scan through 80 modes failed to find any resonance at 2.45GHz. 2.507GHz (outer end plate edge) thru 2.654GHz (centre of end plates) should get you TE013 resonance.
...However, I do not see a direct connection yet between the article in Nature and the work of Igor Pikovski, about quantum decoherence to what Todd has been proposing. The microwave electromagnetic fields inside the EM Drive are carried by photons, which are quantum particles. Photons are capable of displaying quantum coherence and decoherence. The laser, superconductivity and superfluidity are examples of highly coherent quantum systems whose effects are evident at the macroscopic scale.I know of nothing in the EM Drive experiments that has shown a state of quantum coherence, and therefore nothing that has shown that decoherence takes place in the EM Drive. So where is the connection to the EM Drive?Regarding Todd's papers, if he posited quantum coherence, I missed that in his papers. My understanding is the contrary, that his emphasis is on geometric attenuation producing evanescent waves that can carry momentum. Todd is not even looking for a super-high Q, but portrays the tug-of-war between Q storage and attenuation and evanescent waves as what could enable the EM Drive to work.